The primary objective of the proposed research is to delineate the role of memory consolidation in children's word learning. The research will compare two groups, those whose language is developing normally and those who are affected by specific language impairment (SLI). As a group, children with SLI develop smaller, less robust vocabularies than their unaffected age-mates. Difficulties in the initial acquisition of words contribute to the vocabulary problem but little is known about the contribution of later stages of word learning, stages during which the memory of word forms and meanings is consolidated. The clinical and educational implications of this gap in the knowledge base are enormous as robust vocabulary development is vital for successful communication, reading, and academic performance. Current models of consolidation posit time involving sleep as essential to consolidation. Moreover, recent evidence suggests that children with SLI are likely to experience co-morbid sleep problems. Therefore, a second objective is to document the sleep habits of individuals affected by SLI and to determine the role that sleep plays in the consolidation of word forms and meanings. The project is relevant to public health, in particular to the health and well-being of roughly 7% of the population affected by SLI. The project stands to increase understanding of the vocabulary problems characteristic of affected individuals. Furthermore, the project may serve to establish a link between SLI and sleep problems, thereby suggesting new relevant interventions. The three specific aims of the project are (1) to determine whether sleep problems and SLI are associated;(2) to document behavioral patterns of consolidation of word forms and meanings in both normally developing children and those affected by SLI and (3) to determine the extent to which consolidation of word forms and meanings depends upon sleep in both normally developing children and those affected by SLI. The pursuit of these aims begins with a survey of the sleep habits of individuals with and without SLI. Two experiments will follow. The first will extend published work on adults'consolidation (Dumay, Gaskell, &Feng, 2004) to children with normally developing language. The behavioral paradigm measures consolidation of word forms and meanings over time intervals that do or do not involve sleep. The second experiment extends this paradigm to children with SLI and their normally developing vocabulary-matched peers. The project is relevant to public health, in particular to the health and well-being of roughly 7% of the population affected by specific language impairment (SLI). The project stands to increase understanding of the vocabulary deficits characteristic of affected individuals. Furthermore, the project may serve to establish a link between SLI and sleep problems, thereby suggesting new relevant interventions.